Enzymatic Approaches for Structuring Starch to Improve Functionality.

Starch is one of the most abundant renewable biopolymers in nature and is the main constituent in the human diet and a raw material for the food industry. Native starches are limited in most industrial applications and often tailored by structural modification to enhance desirable attributes, minimize undesirable attributes, or create new attributes. Enzymatic approaches for structuring starch have become of interest to the food industry precisely because the reactions minimize the formation of undesirable by-products and coproducts and are therefore considered environmentally friendly methods for producing clean-label starches with better behavioral characteristics.

Microbial Starch-Converting Enzymes: Recent Insights and Perspectives.

Starch is an abundant, natural, renewable resource, and present as the major storage carbohydrate in the seeds, roots, or tubers of many important food crops, such as maize, wheat, rice, potato, and cassava. Uses of native starches in most industrial applications are limited by their inherent properties. Hence, they are often structurally modified after isolation to enhance desirable attributes, to minimize undesirable attributes, or to create new attributes.

Impact of reagent infiltration time on reaction patterns and pasting properties of modified maize and wheat starches.

The impact of granular and molecular reaction patterns on modified starch properties was investigated as a function of the length of time allowed for reagent to infiltrate starch granules. A fluorescent reagent [5-(4,6-dichlorotriazinyl)aminofluorescein] was dispersed in aqueous normal maize or wheat starch slurries (35%, w/v) for 0, 5, 10, 30, or 60min, after which reaction was initiated by increasing the pH to 11.5 and allowing reaction to proceed for 3h.

Effect of high-speed jet on flow behavior, retrogradation, and molecular weight of rice starch.

Effects of high-speed jet (HSJ) treatment on flow behavior, retrogradation, and degradation of the molecular structure of indica rice starch were investigated. Decreasing with the number of HSJ treatment passes were the turbidity of pastes (degree of retrogradation), the enthalpy of melting of retrograded rice starch, weight-average molecular weights and weight-average root-mean square radii of gyration of the starch polysaccharides, and the amylopectin peak areas of SEC profiles. The areas of lower-molecular-weight polymers increased.

Physical modification of food starch functionalities.

Because, in general, native starches do not have properties that make them ideally suited for applications in food products, most starch is modified by dervatization to improve its functionality before use in processed food formulations, and because food processors would prefer not to have to use the modified food starch label designation required when chemically modified starches are used, there is considerable interest in providing starches with desired functionalities that have not been chemically modified. One investigated approach is property modification via physical treatments, that is, modifications of starches imparted by physical treatments that do not result in any chemical modification of the starch. Physical treatments are divided into thermal and nonthermal treatments.

Effects of the order of addition of reagents and alkali on modification of wheat starches.

The objective of this research was to determine if adding reactive reagents to wheat starch granules before addition of alkali (the TRF method) would produce products that are different than those obtained with the conventional procedure (adding alkali before addition of reagent). Laboratory-isolated (LI) and commercial (C) normal (NWS) and waxy (WWS) wheat starches were each reacted with 6 reagents (acetic-adipic mixed anhydride (AAMA), phosphoryl chloride (POCl3), sodium trimetaphosphate (STMP), acetic anhydride (AA), succinic anhydride (SA), octenylsuccinic anhydride (OSA)). Data obtained were similar to those previously obtained with maize starches (Sui, Huber, & BeMiller, 2013).

Preparation and characterization of octenylsuccinylated plantain starch.

Plantain starch was esterified with octenylsuccinic anhydride (OSA) at two concentrations (3 and 15% w/w) of OSA. The morphology, granule size distribution, pasting, gelatinization, swelling, and solubility of granules and structural features of the starch polymers were evaluated. Granules of the OSA-modified starches increased in size during cooking more than did the granules of the native starch, and the effect was greater at the higher OSA concentration.

Effects of the amylose-amylopectin ratio on starch-hydrocolloid interactions.

Combinations of 4 rice starches with amylose (AM) contents of 0%, 15%, 22%, and 28% and 8 hydrocolloids (xanthan, guar gum, CMC, sodium alginate, HPMC, κ-, ι-, λ-carrageenan) were used (4.75% starch and 0.25% hydrocolloid).

Effects of the order of addition of reagents and catalyst on modification of maize starches.

The objective of this research was to determine if adding reactive reagents to starch granules before addition of alkali (TRF method) would produce products that are different than those obtained by adding alkali before addition of reagent. Normal (NMS) and waxy (WMS) maize starches were each reacted with acetic-adipic mixed anhydride (AAMA), phosphoryl chloride (POCl3), sodium trimetaphosphate (STMP), acetic anhydride (AA), succinic anhydride (SA), and octenylsuccinic anhydride (OSA). Almost no or no starch polymer molecule modification occurred when the TRF method and AAMA, AA, or POCl3 were used; less than half as much reaction when SA was the reagent used, and about the same amount of reaction when STMP or OSA were the reagents used (for different reasons).

Relationship of the channels of normal maize starch to the properties of its modified products.

Starches from 5 inbred lines of normal maize with different relative average degrees of channelization (RADC) that could be divided into two groups (2 with RADC values of 1.49-1.52 and 3 with RADC values of 0.

Extraction of polysaccharides from a species of Chlorella.

The objective of this project was to devise a method to recover the total, water-soluble cell-wall polysaccharides of Chlorella. It was found that substantial quantities of polysaccharides could be extracted after treatment of the cells with a mildly acidic solution of sodium chlorite (yield of recovered polysaccharide, 19-22%). Water-soluble (13-19% yield) and 2% NaOH-soluble (3-6% yield) fractions were obtained.

Confocal laser scanning microscopy of dextran-rice starch mixtures.

The microstructure of rice starch and dextran-rice starch mixtures was studied using confocal laser scanning microscopy (CSLM) and scanning electron microscopy (SEM). Surface pores and channels of rice starch were looked for. Channels could not be found in rice starch granules after reaction with 3-(4-carboxybenzoyl)-quinoline-2-carboxaldehyde (CBQCA).

One hundred years of commercial food carbohydrates in the United States.

Initiation and development of the industries producing specialty starches, modified food starches, high-fructose sweeteners, and food gums (hydrocolloids) over the past century provided major ingredients for the rapid and extensive growth of the processed food and beverage industries. Introduction of waxy maize starch and high-amylose corn starch occurred in the 1940s and 1950s, respectively. Development and growth of the modified food starch industry to provide ingredients with the functionalities required for the fast-growing processed food industry were rapid during the 1940s and 1950s.

Effects of protein on crosslinking of normal maize, waxy maize, and potato starches.

Channels of maize starch granules are lined with proteins and phospholipids. Therefore, when they are treated with reagents that react at or near the surfaces of channels, three types of crosslinks could be produced: protein-protein, protein-starch, starch-starch. To determine which of these may be occurring and the effect(s) of channel proteins (and their removal) on crosslinking, normal and waxy maize starches were treated with a proteinase (thermolysin, which is known to remove protein from channels) before and after crosslinking, and the properties of the products were compared to those of a control (crosslinking without proteinase treatment).

The Hofer-Moest decarboxylation of D-glucuronic acid and D-glucuronosides.

Research was undertaken to effect the oxidative decarboxylation of glycuronosides. Experiments with free D-glucuronic acid and aldonic acids were also executed. Both anodic decarboxylation and variants of the Ruff degradation reaction were investigated.

Extension of the Nef reaction to C-glycosylnitromethanes.

Acid-catalysed methanolysis of 3,4,5,6-tetra-O-acetyl-1,2-dideoxy-l-arabino-hex-1-enitol proceeds via a cascade set of consecutive reactions resulting in its regiospecific conversion to a mixture of alpha- and beta-C-L-arabinofuranosylmethanal dimethyl acetals and a mixed internal methyl acetal. Structures of the final products of the overall process provide unique evidence that a kinetically controlled, five-membered-ring closure precedes a six-membered-ring closure in reversible systems capable of giving both five-membered and six-membered all-sp3-atom rings. Determination of the reaction intermediate enabled extension of the Nef reaction to C-glycosylnitromethanes.